Pant-type hygienic articles include a pant-shaped chassis structure and optionally an absorbent core component integrated with the chassis. A major objective when designing pant articles is to make them resemble ordinary underwear as closely as possible. Hence, absorbent articles such as pant diapers, sanitary pants and incontinence pants are designed to fit comfortably and snugly about the wearer. It is also necessary that the absorbent articles provide sealing against leakage of body fluids out of the absorbent article without being so tight that they are uncomfortable to wear. It is further desirable that the articles are capable of being pulled up and down over the hips of the wearer in the manner of a pair of underpants to allow the wearer or caregiver to easily remove a soiled article and to replace it with a new clean article. For all of these reasons, the article chassis is usually made of a material that is elastically stretchable, at least in the areas intended to be applied over the wearer's hips. Furthermore, it is desirable that the chassis surrounding the absorbent parts of the pant article is permeable to air and vapor, i.e. that it is breathable. A breathable article prevents moisture from remaining on the skin of the wearer and is more comfortable and less warm to wear than a non-breathable article. It is also beneficial if the article is soft, smooth and textile-like, so that it does not chafe the skin of the wearer and so that it resembles ordinary underwear as closely as possible.
One type of elastic material for pant articles is a laminate including an elastic film sandwiched between two layers of non-elastic nonwoven material. In order to render the laminate elastically stretchable, it is subjected to an activation treatment. A three-layer, activated laminate is disclosed in International Patent Application No. WO 03/047488. The activated laminate is produced by incrementally stretching an elastic film layer between two non-elastic cloth-like layers. Incremental stretching is carried out by passing the laminate between intermeshing gear rollers. Activation of first elastic laminates by incremental stretching is also disclosed in U.S. Pat. Nos. 5,143,679, 5,156,793 5,167,897, 5,422,172, 5,592,690, 5,634,216 and 5,861,074. The non-elastic cloth-like layers are fully or partially broken or torn during the activation process so that the elasticity of the laminate after activation is governed mainly by the elasticity of the elastic film layer. In the three-layer laminate in WO 03/047488, the non-elastic layers are completely broken so that the elasticity of the activated laminate is substantially the same as the elasticity of the elastic film layer.
The disclosed laminates have excellent comfort characteristics and are soft, flexible, breathable and elastic. However, a major disadvantage with the three-layer laminates disclosed in WO 03/047488 is that the activation process at least partially breaks and destroys the cloth-like layers resulting in a material having decreased tensile strength and puncture resistance in a direction perpendicular to the direction of elasticity of the material. When used as a chassis component in a disposable pant article, the material is easily torn when exposed to the forces arising when putting on or pulling off the pant article. This tearing problem is particularly pronounced for female wearers or caregivers who often have long fingernails that may penetrate and tear the pant material.
Another problem with three-layer laminates in WO 03/047488 is that they have a pre-determined extensibility and elasticity. However, it is often desirable to have different elasticity in different parts of a pant-type article. In order to accomplish this, it is necessary to supplement the elastic panels created from the three-layer laminate with additional elastic elements or to make different parts of the diaper chassis from different laminates. All such extra components are costly and complicate the manufacturing process since they require additional process steps, thus incurring additional processing costs.
In order to remedy the shortcomings of the laminated elastic materials according to WO 03/047488, it has been proposed in WO 2007/133146 to produce a three-layer elastic laminate in a two-step process. The two-step process involves producing a two-layer laminate comprising a non-elastic fibrous nonwoven web and an elastic film. The two-layer laminate is activated by incremental stretching in at least one direction to render the two-layer laminate elastically stretchable. The two-layer laminate is subsequently stretched by 35-200% in at least one direction, the degree of stretching determining the elasticity of the final three-layer laminate. The stretched two-layer laminate is then used in a pant-forming process to create one or more elastic panels in the chassis structure of a pant-type absorbent article by laminating the elastic film of the stretched two-layer laminate to a nonwoven chassis component.
It has been discovered that elastic webs such as the laminates disclosed in WO 03/047488 and in WO 2007/133146 are difficult to process in fast-running machines producing disposable absorbent articles. As a result of necking, the activated and stretched elastic webs tend to curl at the edges, implying that they are difficult to incorporate into high-speed production processes.
A further problem is that the extensibility of the elastic panels in the finished absorbent articles is less than would be expected, implying that the articles will fit only wearers within a limited size range.